Article View: comp.sys.transputer
Article #2676Transputer timing
From: Erick Bizouarn
Date: Wed, 10 May 1989 16:51
Date: Wed, 10 May 1989 16:51
85 lines
2429 bytes
2429 bytes
We have some questions on the notion of time of the transputer. It has a strange behavior. Consider the following example where we measures the execution time of the ldc (load constant) instruction. The time does not always increase with the number of the instruction in the measured loop. We have obtained the following results on a T414: ----------------------------------------- | number of ldc inst | execution time | ----------------------------------------- | 0 | T = 16832 us. | ----------------------------------------- | 1 | T - 960 us. | ----------------------------------------- | 2 | T - 1984 us. | ----------------------------------------- | 3 | T - 512 us. | ----------------------------------------- | 4 | T + 2048 us. | ----------------------------------------- ------------------------------------------------------------------------------- .text _mess: .ascii "time = %d us.\12\0" .globl _main _main: adjw -3 ldc 0 sttimer ldtimer stl 1 ldc 10000 stl 2 .align 2 ; alignment on a divisible by 4 boundary. L0: ### ldc 0 ..... (n times) ldc 0 ### ldl 2 adc -1 stl 2 ldl 2 eqc 0 cjmp L0 ldtimer ldl 1 sub ldc 64 ; for low priority timer mul adc -16832 ; time for a loop without any ldc 0 instruction. ldc _mess-L1 ldpi L1: ldl 4 call _printf adjw 3 ret -------------------------------------------------------------------------------- Where is the mistake ??? May a longer program be executed faster ? Perhaps it will be explained by instruction prefetch, but we would like an detailled explanation. Furthermore is there a means to write out of the memory of the INMOS B004 transputer card without halting the transputer. Thanks in advance for any hint. ******************************************************************************** Bizouarn Erick L.R.I. (Universite d'Orsay) France E-mail: eb@lri.lri.fr ********************************************************************************
Technical Details
Message-ID:
<412@lri.lri.fr>Path:
arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!sun-barr!texsun!pitstop!sundc!seismo!uunet!mcvax!inria!crcge1!lri!ebShow Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!sun-barr!texsun!pitstop!sundc!seismo!uunet!mcvax!inria!crcge1!lri!eb From: eb@lri.lri.fr (Erick Bizouarn) Newsgroups: comp.sys.transputer Subject: Transputer timing Message-ID: <412@lri.lri.fr> Date: 10 May 89 16:51:51 GMT Sender: eb@lri.lri.fr Lines: 85